Answer to Question #11105 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Airplanes

The following question was answered by an expert in the appropriate field:

Q

I have heard that you should remove one shoe when flying and put your foot on the metal support frame of the seat in front of you to ground yourself to the airplane frame and help mitigate damage from radiation at 10,000 m. I doubt this is true. Is there any technical basis for the idea that grounding yourself to an airplane during flight will mitigate your cosmic radiation dose at high altitudes?

A

First, recognize that an aircraft in flight is not grounded. Obviously there is no physical connection to earth. In a manner similar to an automobile, where the negative side of the electrical system is connected to the chassis because its rubber tires insulate it from earth, the entire metal frame of a plane serves as a conducting part of the electrical circuits. In fact, to avoid any possibility of a lightning strike creating a voltage difference somewhere in the aircraft, particular attention is paid to making certain that every hose and coupling is connected to the airframe. In this way there is no danger of an accidental ignition in those areas where fuel vapor can be found.

Cosmic radiation of the sort that impacts passengers and crew is composed primarily of energetic particles released by the interaction of solar and galactic protons with the earth's atmosphere. This radiation essentially strikes the body in a way that can be imagined as if they are the pellets from a shotgun, albeit on an atomic scale.

There is no way that connecting oneself to the airframe has any influence on this process. When the body's cellular structure is "hit" by a radiation particle, the transfer of energy by the collision is what damages the cell. The electrical potential of the individual at that time has no influence whatsoever. So, although any static charge you may generate by wiggling around in your seat can be bled off by a connection to the metal structures around you, there is no protection from cosmic radiation by this type of "grounding."

Robert Barish, PhD, CHP

Answer posted on 30 September 2014. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.